Caves are cavities that form in hillsides, in cliff walls, and underground, and are accessible at Earth's surface. Typically, they form in soft, fractured, or soluble rock as a result of natural mechanical and chemical processes that continue over th...ousands of years. This interactive activity from NOVA Online offers animated explanations for how ocean waves, lava, slightly acidic groundwater, and, in a supporting role, microbes account for the variety of cave formations on Earth.[more]

The most common process by which limestone caves form involves carbonic acid — or weakly acidic groundwater — as the primary agent. When carbonic acid contacts limestone, it dissolves minerals in the rock. If enough water to saturate the rock is pres...ent over a long time period, cavities and entire underground cave networks can form. Recently, a radical new theory has been proposed that identifies another cave-forming agent: sulfuric acid. This video segment adapted from NOVA identifies the mysterious source of the sulfuric acid, which, unlike carbonic acid, does not readily form in nature. Closed captioning included. (05:42)[more]

With over 365 known miles of cave passageways, Mammoth Cave is the world's longest cave. Besides its spectacular size, Mammoth Cave has an almost surreal beauty. Remarkable stories of human history, 350 million-year-old rocks and its fascinating anim...als adapted to life in the dark make Mammoth Cave a place you must visit. (01:09)[more]

This video provides highlights from Mammoth Cave National Park DVD Postcard. It includes beautiful footage by Russ Finley edited to inspiring music. The best of Mammoth Cave - majestic tunnels, interesting formations, scenery, and more. In a ready-to...-mail mailer for family and friends! The full DVD is available on location and from www.finleyholiday.com. (06:20)[more]

At first glance, Wyoming's Kane Cave exhibits few characteristics of the world's most picturesque caves — it lacks mineral deposits, including stalactites and stalagmites, which decorate most cave ceilings and floors. Although the cave is not small, ...it pales in size against more massive ones, like those of New Mexico's Carlsbad Caverns. However, it is not its size that draws scientists to Kane Cave, but another compelling aspect of the cave. In this video segment adapted from NOVA, watch as scientists conduct a simple experiment to determine whether microbes that inhabit the cave could actually be contributing to the cave-formation process. Closed captioning included. (04:12)[more]

From DragonflyTV. Isabel and Emily are spelunkers! That means they like exploring caves. In this video, the girls head to Carlsbad Caverns in New Mexico to help with an ongoing cave swallow study. Carlsbad Caverns is made up of over 100 caves, includ...ing the largest cave chamber in the United States.[more]

From Dragonfly TV. Marie and Michelle explore the California Cavern (10 miles of underground tunnels and chambers) to answer this DFTV question: How do cave formations change as you travel to the deepest parts of the cavern?
Cave formations called... speleothems are mineral deposits that build up on the ceiling, floors and walls. The two most common are the ones that grow from the ceiling down, called stalactites, and others that grow from the floor up, called stalagmites. The girls looked at the number of speleothems that were found in three different locations to determine if there were more formations deeper down, or more near the cave's surface.[more]

For certain life forms on Earth, conditions that humans and other familiar organisms find hospitable can actually be deadly. Instead of a moderate climate with an atmosphere rich in nitrogen and oxygen, these organisms thrive in very hot or very cold... temperatures, or in caves or deep waters where no light penetrates. In this video segment adapted from NOVA, scientists analyze communities of cave-dwelling microbes that live off simple inorganic compounds like iron and sulfur. Based on their findings, the scientists consider whether life might also exist on other planets that contain similar primitive conditions. (04:42)[more]

Caves are cavities in Earth that typically form over thousands of years through natural mechanical and chemical processes. Most underground caves form as slightly acidic groundwater dissolves limestone rock. The result is a subterranean environment o...f caverns and, in some places, vast networks of smaller, interconnecting chambers. This interactive activity, adapted from The Virtual Cave, by Dave Bunnell, provides a detailed map of a solution cave system with links to images and descriptions of its many formations.[more]

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